Small Form-factor Pluggable (SFP) modules are used in various telecommunication and data networking applications to interface between a printed circuit board in a network device and a network cable (which may be electrical or fiberoptic). Typically, the SFP receptacle is mounted on the printed circuit board with appropriate electrical connections to the circuit traces on the board, and a connector at the end of the cable plugs into the receptacle. The connector itself commonly contains signal conversion circuitry and is therefore referred to as a “transceiver.”
The mechanical and electrical characteristics of various SFP modules have been defined by industry organizations. For example, Quad Small Form-factor Pluggable (QSFP) modules support four parallel communication channels at 10 Gb/s. The mechanical and electrical characteristics of QSFP modules are described in the SFF-8436 Specification for QSFP+ Copper and Optical Modules (Revision 3.4, November, 2009).
Other types of SFP modules can have different mechanical and electrical characteristics, as defined by the respective standards. For example, Octal Small Form Factor Pluggable (OSFP) is a new form factor with eight high-speed electrical lanes that will initially support 400 Gbps (8×50G). Electrical and mechanical specifications for OSFP were recently released by the OSF Multi Source Agreement (MSA) Group and are available on line at osfpmsa.org. According to the specifications, OSFP connectors are slightly wider and deeper than the QSFP form factor and have an integrated heat-sink that is said to improve thermal performance. The OSFP MSA Web site suggests that it is possible to build an adapter that supports existing 100G QSFP optics modules in an OSFP cage.
Adapters for connecting SFP plugs of a given type to an SFP receptacle of a different type are known in the art. For example, U.S. Pat. No. 7,934,959, whose disclosure is incorporated herein by reference, describes an adapter includes a mechanical frame, which is configured to be inserted into a four-channel Small Form-Factor Pluggable (SFP) receptacle and to receive inside the frame a single-channel SFP cable connector. First electrical terminals, held by the mechanical frame, are configured to mate with respective first pins of the receptacle. Second electrical terminals, held within the mechanical frame, are configured to mate with respective second pins of the connector.
Circuitry couples the first and second electrical terminals so as to enable communication between the connector and one channel of the receptacle while terminating the remaining channels of the receptacle.